Monday, December 12, 2011

Still monitoring on modern moving coil loudspeakers? Perhaps you need some vintage electrostatics to really hear what's on your recording?

By David Mellor

You might think that the photo shows a pair of electric radiators. But no, they are actually some of the finest loudspeakers ever designed.

And the design dates from 1957!

I have no interest in vintage equipment for its own sake, and I'll use whatever sounds good, whatever its age. I tell you that because I don't want you to think I'm saying these speakers are good because they are old. That would be nonsense. They are good because their design is amazing. And, well-maintained of course, their age is immaterial.

The photo shows examples of the Quad ESL 57 electrostatic loudspeaker. '57' because the design dates, as I said, from 1957. If you want something more up-to-date then there's also the ESL 63 to consider :-)

The photos are from Ebay seller significantsound, which I reproduce with permission. The speakers illustrated are, at the time of writing, available to buy here...

Now, Question Number 1 is why are these speakers so good?

The answer to that comes from another question - why are moving coil loudspeakers so bad? (Almost all loudspeakers are of the moving coil design. You have some right there in your studio, and your living room, and your car, and tiny ones plugged into your iPod.)

The problem with moving coil loudspeakers is mainly to be found in the low-frequency drive unit, or woofer. The diaphragm has to be big to shift a lot of air. It has to be light so it can move easily. It has to be stiff so that it doesn't bend and produce distortion. And it has to satisfy all three of those conflicting requirements, which it can't.

Modern moving coil loudspeakers are amazingly good, but there is always the problem of transmitting the movement of the voice coil in the center of the drive unit, all the way to the edge of the diaphragm, without the diaphragm bending. This problem is inherent to the design.

But the diaphragm of the electrostatic loudspeaker can be driven over its entire surface area. It can be extremely light, yet still not bend. The result is a distortion-free, airy and accurate sound. The motto of Quad, the manufacturer, was and continues to be "The closest approach to the original sound". With just cause.

So now for Question Number 2 - If electrostatic loudspeakers are so good, why do we still use moving coil designs?

One answer to that is that it is cheaper to produce moving coil loudspeakers. Or to put it another way, electrostatic loudspeakers can't be produced cheaply.

Another is that electrostatics don't handle high levels and lots of bass so well as moving coils.

Another is that they are bi-directional, so you have to consider where the sound from the rear goes.

Another is that they need mains power.

Another... Well that's probably enough. They are simply not as practical as the moving coil.

And...

Although not as accurate, many people prefer the 'speakery' sound of the moving coil design.

I am to an extent eulogizing the electrostatic loudspeaker, and it is a fact that I don't have them in my home. But I certainly do recommend you take any opportunity you can to listen to some. You will be amazed how non-speakery loudspeakers can be!

Tuesday, December 6, 2011

There's no such thing as too much compression, if it sounds good. But there is a point where things might get worse, not better...

By David Mellor

Do you ever look at your compressor's gain reduction meter? Actually, it should be called a level reduction meter but 'gain reduction' is a term that has been handed down by history, so I will continue to use it.

Obviously, you should judge compression by ear, but it is helpful to have a visual indication of what's going on. If you want to hear more compression, then you need to see more segments on the gain reduction meter lighting up (or the needle going down more deeply), and faster movements.

But here's something you should look out for - while the instrument is playing (or singer singing), does the meter always show some degree of gain reduction? Even in the quietest (but still playing) sections?

If so, then you are indeed applying too much compression, through setting the threshold too low.

You will hear the effect of this in the transitions from not-playing to playing. Just after the gaps in playing in other words.

When the instrument comes in each time, the compressor suddenly has to leap into deep compression and this leap, though momentary, will probably sound ugly.

But if you set the threshold so that the gain reduction meter reads only a decibel or two in the quietest sections, the compressor never has to compress more than it needs to. The transition from not-playing to playing will be much smoother.

Of course, if you use a compressor for warmth, such as a variable-mu compressor or digitally-mimicked version, then deep compression might give you the sound you are after and you might accept a little roughness in the transitions.

Other than that however, it is a good guideline to set the threshold so that at the very quietest part of the recording, the amount of gain reduction drops almost to zero.